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SubjectRe: [Linux-fbdev-devel] fb: modedb uses wrong default_mode
On Mon, 20 Nov 2006 16:48:05 +0000 (GMT)
James Simmons <jsimmons@infradead.org> wrote:

> > > db = modedb;
> > > dbsize = ARRAY_SIZE(modedb);
> > >
> > > if (!default_mode)
> > > default_mode = &db[DEFAULT_MODEDB_INDEX];
> > > if (!default_bpp)
> > > default_bpp = 8;
> > >
> > > db will always be set.
> >
> > I think we do need dbsize, and that the code which I have now:
>
> I really don't trust dbsize. The driver writer can pass in the wrong
> number.

That would be a bug.

> Whereas ARRAY_SIZE will always be correct. Lets take the position
> that we use dbsize then we need to test if dbsize is greater than the
> really size of the modedb. The dbsize parameter was for the days before we
> had ARRAY_SIZE.
>
> > int fb_find_mode(struct fb_var_screeninfo *var,
> > struct fb_info *info, const char *mode_option,
> > const struct fb_videomode *db, unsigned int dbsize,
> > const struct fb_videomode *default_mode,
> > unsigned int default_bpp)
> > {
> > int i;
> >
> > /* Set up defaults */
> > if (!db) {
> > db = modedb;
> > dbsize = ARRAY_SIZE(modedb);
> > }
>
> if (dbsize > ARRAY_SIZE(db))
> dbsize = ARRAY_SIZE(db);

We can't do ARRAY_SIZE on a random pointer like this: the compiler needs to
see the full definition of the array itself, and that is back in the
caller's compilation unit.


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